Water-curable polyolefins have found use in the prior art in the area of adhesives. Advantages of water-cured adhesives result from the avoidance of a free-radical curing process, the elimination of flammable peroxide initiators and corrosive crosslinking acceleration agents associated therewith, and the ability to cure with water, often using ambient moisture.
However, there remain two primary disadvantages associated with as-mixed water-curable adhesives: (1) organic solvent based application techniques; and (2) the tendency for small molecule silane condensation catalysts to migrate to the adhesive surface.
The use of organic solvents during the process of applying the adhesive composition to a substrate surface not only complicates manufacture by the requirement of a solvent removal step, but can also pose health and environmental hazards. Migration of small molecule silane condensation catalysts (many of which are also commonly used as slip and/or anti-block additives) to the coating interface can result in adverse adhesion properties.
As far as the Applicant is aware, there is no prior art technology for eliminating the use of organic solvents and reducing silanol condensation catalyst migration.
U.S. Pat. Nos. 4,753,993; 4,707,520; 4,593,072; 4,593,071; 4,579,913; 4,575,535; 4,526,930; 4,369,289; 4,328,323 all to Keogh disclose thermoplastic polymers having hydrolyzable, pendant silane moieties which impart water-curability to the polyolefin polymer. These polymers are stated to be useful in extrusion coating operations, especially as extrusion coated insulation for electrical conductors wherein external moisture conditions gradually improve the polymer toughness.
U.S. Pat. No. 4,726,869 to Matsui et al. discloses a method for joining shaped articles of cured polyolefin utilizing a water-curable polyolefin applied to one or both surfaces in the form of a low viscosity liquid applied with a brush, wherein the polyolefin is grafted with an unsaturated organic silane monomer.